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<title>Section 8.17.&nbsp; Summary</title>
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<h3 class="docSection1Title">8.17. Summary</h3>
<p class="docText">A thorough understanding of the UNIX System's process control is essential for advanced programming. There are only a few functions to master: <tt>fork</tt>, the <tt>exec</tt> family, <tt>_exit</tt>, <tt>wait</tt>, and <tt>waitpid</tt>. These primitives are used in many applications. The <tt>fork</tt> function also gave us an opportunity to look at race conditions.</P>
<p class="docText">Our examination of the <tt>system</tt> function and process accounting gave us another look at all these process control functions. We also looked at another variation of the <tt>exec</tt> functions: interpreter files and how they operate. An understanding of the various user IDs and group IDs that are providedreal, effective, and savedis critical to writing safe set-user-ID programs.</P>
<p class="docText"><a name="idd1e62010"></a><a name="idd1e62015"></a><a name="idd1e62020"></a><a name="idd1e62025"></a><a name="idd1e62030"></a><a name="idd1e62035"></a><a name="idd1e62038"></a><a name="idd1e62043"></a><a name="idd1e62048"></a><a name="idd1e62053"></a><a name="idd1e62058"></a><a name="idd1e62063"></a><a name="idd1e62068"></a><a name="idd1e62073"></a><a name="idd1e62078"></a><a name="idd1e62083"></a>Given an understanding of a single process and its children, in the next chapter we examine the relationship of a process to other processessessions and job control. We then complete our discussion of processes in <a class="docLink" href="ch10.html#ch10">Chapter 10</a> when we describe signals.</p>

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